Air conditioning unit



Feb. 20, 1934. c. M. ASHLEY ET AL AIR CONDITIONING UNIT Filed June 1; 1951 s Sheets-Sheet 1 ATTORNEY Feb. 20, 1934. c M. ASHLEY ET AL 1,948,156

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INVENTOR C/i/PL YLE M. Ash 15 mvp 1 1 7 BY V A/d'F/VT 8-D4Y ATTORNEY Feb. 20, 1934. c. M. ASHLEY ET AL AIR CONDITIONING UNIT 3 Sheets-Sheet 3 Filed June 1, 1931 7, Ann

ATTORNEY awe; r45 N. ASHLE BY WNC'f/VT \9- DAY Patented Feb. 20, 1934 UNITED STATES AIR CONDITIONING UNIT Carlyle M. Ashley, South Orange, and Vincent S.

Day, Summit, N. J., assignors to Carrier Research Corporation, Newark, N. J., a corporation of New Jersey Application June 1, 1931. Serial No. 541,278

Claims.

This invention relates to air conditioning ap paratus and more particularly to a gas-fired system for controlling the temperature and relative humidity of enclosures under winter operating 6 conditions.

The general object of the invention is to provide a compact and efficient unit adapted to maintain a desired temperature responsive to varying conditions afiecting a given enclosure,

10 and independently to control the relative humidity of the enclosure. 7

Another object of the invention is to-route a plurality of streams of air through an air conditioning unit so that diiferent portions of the total volume treated by the unit will be variously affected in temperature and moisture content. Thus, for example, one volume of air will be raised and maintained at a temperature above the condensation point of gaseous prodnets of combustion employed in the unit, whereas another volume will be treated so that its temperature will be below said condensation point, whereas still other volumes will be routed independently for humidification and other purposes.

A feature of the invention resides in the provision of a plurality of heat interchanging devices separable in structure and so assembled that the temperature of air and gases in each of said devices is within a range appreciably diifer- 3o ent from that within the other of the devices.

Since it is desirable to use gas, either manufactured or natural, as a fuel in heating and air conditioning systems, the effect of corrosion due to condensation resulting after the gas firing or combustion process must be guarded against by the use of a material capable of withstanding corrosive action. If, however, the range of temperature of gases is controlled so that condensation takes place at a given point or within a limited area, then the use of corrosion-resistant metal is confined to this area with consequent saving both in initial cost and in operation and with increased effectiveness in heat interchange efiiciency.

A further feature resides in the interconnection of two interchange devices by a joint including extended surface capable of dissipating heat. This not only enables the use of low temperature packing between one interchanger serving high temperature gases and another serving relatively colder gases, but effectively separates one from the other, so that little, if any, heat interchange will result between the two at the point of juncture.

Another object of the invention is to provide a fire box arrangement in combination with a gas-fired air conditioning unit, whereby the heat evolved within the fire box will be concentrated Within. one of a plurality of heat interco changing devices, and employed to heat a relatively small volume of air, thereby assuring a temperature within said device always above the condensing point of the gaseous products of combustion. In consequence, this device need not be made of material capable of withstanding corrosive action. The other of the interchangers, however, may heat a much larger volume of air, and do so with the partially spent gases coming from the first, so that a much lower temperature range below the condensation point is effectively established.

Another feature covers the use of fins or extended surface on top of the fire box adapted to promote radiation and designed to expand and contract without buckling or making noise. In order to assure intimate contact of a relatively small volume of air (compared to the total volume handled by the system) with the top of the fire box, a shield is provided on the finned surfaces with a restrictive element serving to limit the amount of air contacting with the fire box and fins, as well as to increase the velocity of said air, with the result that turbulence will be induced in this volume of air and cause an increase in the rate of heat transfer between the top of the fire box and the contacting air volume. At the end of its travel in contact with the top of the fire box, said volume of air will be further subjected to turbulence, so that diffusion will be had before it enters the connected heat interchanger.

Another feature of the invention provides for the positioning of an interchanger arrangement in a gas-fired air conditioning unit, whereby positive drainage of condensate is effected and metal otherwise subjected to corrosion protected against re-evaporation and concentration of acids in condensate.

Another feature covers the use of a drainage device whereby condensate from the system, as well as possible overflow from a humidification arrrangement are collected at one point for ready disposal.

Other objects and features, and advantages in design and construction-making for economy in manufacture and operation, will be more apparent from the following detailed description of one form of the invention to be read in connection with the accompanying drawings, in

which:

Fig. 1 is a representation, partly in section, of an arrangement of apparatus, in unit I form, adapted to carry out the invention,

Fig. 2 is a detailed view of a section through the interchanger arrangement employed,

Fig. 3 shows the layout of the fire box, the extended surface on its upper side and the means for directing air through the interchanger,

Fig. 4 is a plan view, partly in section, of the details shown in Fig. 3,

Fig. 5 is a perspective view of the fire box' and interchanger assembly, showing also the relation of the humidification system to the heating apparatus, and

I Fig. 6 illustrates the method of draining condensates from the system,as well as inspecting the "interior of the interchanger arrangement.

Considering the drawings, similar designations referring to similar parts, numeral 7 generally designates aunit air conditioning apparatus comprising an air inlet adapted to be connected to outdoors or any other source of air supply, air filters 9 of any suitable design, fan 10 and fire box 11. The fire box houses a set of gas burners 12 serving heat interchangers 13 and 14 and also accommodates an independent set of burners 15 serving drum 16 of a humidification arrange ment forming part of the system. The drum l6 and burners 15 are effectively segregated by shield 17 from the remainder of the fire box. Sealing ring 18 is held by spring 19 against the fire box and prevents leakage of products of combustion from the fire box at the points where pipes 20 of the humidification system enter the fire box.

Interchanger 13'connects to the fire box and discharges products of combustion into a secondary interchanger 14 joined to" header 21 suitably'fastened to the outer frame of the unit. The header connects to collecting chamber 22 leading to diverter 23 and flue 24. Air collecting tube 25 has its inlet adjacent interchanger 13 and withdraws heated air to the flue. In practical operation, air will enter through inlet 8 and after passing through the filter 9, will be sent to the conditioning apparatus by fan 10. Due to the arrangement of the apparatus and the provision of partitions 26 and shielding 27, a por-' tion'of the air will be sent through the first in terchanger. Another portion will be sent through the second interchanger, whereas a third portion 'willnot be sent through the heating equipment, but by-pass the interchangers'and' proceed to evaporator 28 of the humidification arrangement. All air will finallyleave through outlet 29 and then generally bedistributedthrough any desired system of ducts, connected to the outlet. The products of combustion'will proceed from the fire box through interchangers' 13 and 14, header 2'1 and out to thefiue through collecting chamber 22 and diverter 23.

Considering the interchanger arrangement, with particular reference to Figs. 2 to 5, the products of combustionfirst'enter interchanger 13, which we shall designate as first interchanger, from the fire box, and then pass to second interchanger 14. Since the products of combustion leaving the fire box are at temperatures at times far in excess of 600 or700 F., it is necessary that the interchanger be made of metal capable of withstanding a high temperature. Second 'interchanger 14, however, need notbe made-of material capable of withstandingsuch high temperatures, since a lower temperature range is here maintained and the more important consideration is to guard against corrosive action resulting from condensation of products of combustion at the lower temperatures. The feature of the design, therefore, resides in having'a' first interchanger wherein a range of temperature is maintained above the condensation point of the products of combustion, and a second interchanger whereinconderlsationtakes place. As a result, the first-interchanger may be made of a metal which withstands hightemperatures but which is not subject to corrosiveaction, whereas the second interchanger is of material impervious to corrosive'action and capable merely of withstanding lower temperatures. This feature isof importance in that many'elements, such aslead, for example, can successfully withstand corn)- s'ion but cannot be used with high temperatures, and correspondinglymany' metals can withstand high temperatures," but are subject to corrosive action. The provisionof two temperature ranges enabks obtaining maximum heat interchange efficiency with positive economy both in first cost and maintenance. Openings 30 of the first interchanger and open: ings 31 of the secondihterchan'ger' are designed to assure maximum heat interchange eifect and by presenting different surface areas resisting free flow of 'air"to*the"outlet', further serve to proportion the air volumes handled; i

* It'may be noted that the crown sheet ofthe fire box inclines upwardly to the first interchanger. The temperaturein the first interchanger is therefore substantially that of the products of combustion leaving the fire box. The crown sheet is provided with fins 32 which may be welded to the fire box or provided in the form of corrugations. These fins are in the'nature of "ex tended surface'and; serve to draw off heat from the fire box, thereby imparting a cooling effect. The fins serve an exceedingly important purpose, in that air drawnunder sheet 33 and in close contact with these extended surfaces on the crown sheet will be heated almost to the temperature of the products of combustion in the'fire box, and always at a point above the condensation temperature of the products of combustion. 1 The passage of the air will, of course, produce'the afore said cooling effect of the fire box by rapidly withdrawing heat therefrom, and the provision or entering bead 34 constrains the entering passage so that the velocity is increased sufiiciently for adequate cooling. Bead 35 at the extremity of sheet 33, at the upper end of the passage, imparts turbulence to'the air leaving the fins and causes greater diffusion. Theair then passes up through the openings 30, in the form of tubes, of the first I interchangerand out through outlet 29.

Partition 36 bars any air entering the first interchanger except that passing beneath bead 34 and in contact with fins orextended surfaces 32.

The air going through second interchanger 14 will not be heated to as great a degree as the relatively smaller volume of air which contacts with the crown sheet of the fire box and goes through thefirst interchanger. Thisisfdue to the lower temperature of the products of combustion which have spent part of their heat in the first interchanger prior to entering the second. Also, as is evident from the illustration, a greater volume of air will be sent through the second interchanger than goesv through'the first. The

temperature 'ofthe second interchanger will.

therefore, drop below the condensation point of the products of'combustion, at least'at the por'-' tion'of'the interchanger near header 21. The

condensate will drip down the sides of innerpassages 37 andbe collected by drips 3'8 emptying into the bottom of header 21. As may be "noted in Fig. 6; the bottom-of the headermay be sloped for a connecting drain pipe 39 leading' 'to a'collecting chamber 40; Any method from chamber 40 may be utilized. H V W Interchangers 13 and 14 are *conn'ected--to; 'ether-by' a joint which also aids in'ma'i'ntainof disposition j ing the desirablei temperature diflerencebetween i the two'interchangers. I Thus, each-" -interchang er has a flanged extremity or suitable integral extended surface 42 which are joined together for supporting flanges 43 suitably fastened together as by bolts 44. The flanged joint will radiate heat and this dissipation of heat is suflicient to lower the temperature so that a low temperature packing may be used which would be incapable of withstanding the efiects of the temperature produced in the first interchanger.

While fins 32 are shown on top of the crown sheet, it is apparent that similar extended surface could be used on other sides of the fire box for similar purposes.

Applicants employ baffles, such as 2'7, shown in Figs. 1, 3 and 5. These baffles may be in front and at the sides of the fire box and guide the air at high velocity over the fire box, in order to obtain the maximum possible cooling of the fire box walls. Furthermore, they act as shields to prevent the radiant heat from the fire-box from directly striking the casing or walls of the unit,

thereby serving to divide the air from the fan intotwo main streams, hot streams on one side, contacting with fire box and heat-interchangers, and cool streams adjacent the outer walls or casing of the unit. The outer walls of the unit may thus be made of metallic substance without necessitating interpositioning of materials such as fire brick, etc.

The humidification: arrangement, as moreparticularly pointed out in copending applications Serial No. 541,242, filed June 1, 1931, and Serial No. 541,180, filed December 22, 1931, comprises evaporator trough or pan 28 connecting outer channels or pipes 20 and heating drum 16 served by independent humidity control burners 15. Water within drum 16 will be heated by the flames from burners 15 and consequently, due to its reduced specific weight, will rise through one of the pipes 20 to the evaporator pan 28. As the water cools, it will settle to the bottom of pan 28, pass through the other pipe 20 and return to the drum 16 to be reheated. As some of the water from the pan is evaporated to humidity the air passing thereover, it becomes necessary to replace it. This is done by a floatrarrangement such as is shown and described in copending application, Serial No. 541,242, filed June 1, 1931. Preferably, the make up water is introduced proximate to one of the pipes 20, with the result that a temperature differential between the two pipes 20 is positively established. A complete thermo siphon circulation system is thereby afforded and the air routed between partition 26 and the outer walls of the unit will be deflected by sheet 45 on to the surface of the water in the pan. This deflection increases the evaporation from the pan and so maintains the water temperature at a relatively low point. Any suitable means may be employed for maintaining a desired level of water in the pan. as by a float valve means. and overflow may be taken care of by drain 46 (see Fig. 6) leading from outlet 4'7.

The header 21 has an opening therein accommodating hand cover 48. The inside of the interchanger arrangement may thereby be reached and it also serves as a blowout door in case of explosion.

Draft diverter 23 is provided with a gutter 49 for collecting and returning any condensate resulting due to condensation from products of combustion on its relatively cooler surfaces. As illustrated, air surrounding the diverter may enter it through opening 50 and thus dilute the flue gases. To minimize the corrosive action apt to occur if the products of combustion were permitted to condense freely, air collecting tube 25 withdraws some high temperature air from the I matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Having described our invention, what we claim as new and desire to secure by Letters Patent, is: 1. An air conditioning apparatus comprising a casing, a first interchanger and a second interchanger in said casing, a firebox for supplying products of combustion to said interchangers in succession, a fan for discharging a volume of air into said casing, and means for diverting a small portion" ofsaid'air'volum'e in contae't' with said first interchanger and a larger portion in contact with said second interchanger.

2. In a combination of air conditioning apparatus, a casing, a first interchanger, a second interchanger, a firebox in communication with said interchangers, a fan for supplying a volume of air to said casing, and a ballle for diverting a portion of said airin-contact with'said-firebox and said first interchanger, the remainder of said air passingin contact with said second inter-- changer.

3. In a combination of air conditioning apparatus, a casing, a firebox in said casing, a first interchanger in communication with said firebox, a second interchanger in communication with said firstinterchanger, a fan for-supplying a volume of air to said casing, a baifle for directing a small portion of said air over saidfirst interchanger and a larger portion over said second interchanger, and a chamber for mixing said volumes of air subsequent to their passage in contact with said interchangers.

4. In a combination of air conditioning appa: ratus, a casing, a firebox in said casing, fins on a portion of said firebox, a first interchanger, a second interchanger, a fan for supplying a volume of air to said casing, and a bafiie for diverting a small portion of said air in contact with said fins and said first interchanger, the remaining larger portion of said air contacting with said second interchanger.

,5. In a combination of air conditioning apparatus, a casing, a first interchanger adapted to withstand high temperature, a second interchanger adapted to withstand corrosion, a firebox for supplying products of combustion to said interchangers in succession, a fan for supplying air tosaid casing, and means for proportioning said air volume between said interchangers to prevent condensation of products of combustion 

